/* ------------------------------------------------------------------------
 *
 * geqo_mutation.cpp
 *
 *	 TSP mutation routines
 *
 * IDENTIFICATION
 * src/gausskernel/optimizer/geqo/geqo_mutation.cpp
 *
 * -------------------------------------------------------------------------
 */
/* contributed by:
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
   *  Martin Utesch				 * Institute of Automatic Control	   *
   =							 = University of Mining and Technology =
   *  utesch@aut.tu-freiberg.de  * Freiberg, Germany				   *
   =*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
 */
/* this is adopted from Genitor : */
/*************************************************************/
/* 															 */
/* 	Copyright (c) 1990										 */
/* 	Darrell L. Whitley										 */
/* 	Computer Science Department								 */
/* 	Colorado State University								 */
/* 															 */
/* 	Permission is hereby granted to copy all or any part of  */
/* 	this program for free distribution.   The author's name  */
/* 	and this copyright notice must be included in any copy.  */
/* 															 */
/*************************************************************/

#include "postgres.h"
#include "knl/knl_variable.h"
#include "optimizer/geqo_mutation.h"
#include "optimizer/geqo_random.h"

void geqo_mutation(PlannerInfo* root, Gene* tour, int num_gene)
{
    int swap1;
    int swap2;
    int num_swaps = geqo_randint(root, num_gene / 3, 0);
    Gene temp;

    while (num_swaps > 0) {
        swap1 = geqo_randint(root, num_gene - 1, 0);
        swap2 = geqo_randint(root, num_gene - 1, 0);

        while (swap1 == swap2)
            swap2 = geqo_randint(root, num_gene - 1, 0);

        temp = tour[swap1];
        tour[swap1] = tour[swap2];
        tour[swap2] = temp;

        num_swaps -= 1;
    }
}
